This invention relates generally to electrical water-resistant switches useful in timepieces which require external pushbuttons or switches to perform various functions such as setting, updating or changing the mode of operation of the timepiece. More particularly, this invention relates to an improved water-resistant rocker switch for a wristwatch which can be used under water by divers, but which is also generally usable in water-resistant watches of all types.
The provision of water-resistant seals for members such as watch crowns or pushbuttons operating internal mechanisms from the exterior of a timepiece have been known for many years. Generally the problem is to allow for sliding or rotary movement of a stem extending through a hole in the bezel without allowing leakage. Many types of gasket and seal arrangements have been suggested in the prior art.
In electric or digital watches, the watchcase or bezel is often at ground potential and a grounded pushbutton makes contact with switching terminals located inside the case. A typical arrangement is shown in U.S. Pat. No. 4,031,348 in the name of N. Eberhardt issued June 21, 1977, wherein a resilient sealing member for a pushbutton assembly in a watch serves as a spring member and also may be conductive to assure electrical contact between the pushbutton member and the watchcase. Unless conductive elastomers are used, some means of providing electrical contact between the moving member and the case is necessary.
A water-resistant pushbutton switch for a watch utilizing an adhesive conductive elastomer to provide a water-resistant seal providing spring return of an external pushbutton making switching contact inside the watch is also illustrated in U.S. Pat. No. 3,973,099 issued to James Morris, Sr. On Aug. 3, 1976. This patent requires a conductive elastomer to provide grounding contact between the pushbutton and the case. Another type of seal is shown in U.S. Pat. No. 3,946,182 issued to P. Holder on Mar. 23, 1976 employing a flexible insulating diaphragm member as a seal and requiring a large number of parts in the assembly. Other types of switches utilizing springs and sliding O-rings are illustrated in U.S. Pat. No. 3,783,607 issued to Walter Feurer on Jan. 8, 1974 and U.S. Pat. No. 3,838,568 issued to Zurcher et. al. on Oct. 1, 1974.
The foregoing constructions which employ conductive elastomers are subject to difficulties with making the proper electrical connections, while switches depending upon sliding metallic contacts are subject to leakage problems. Furthermore, if the timepiece is to be truly capable of withstanding pressure under water, it must employ a construction which is not subject to actuation by large pressure difference between the inside and the outside of the watchcase.
Accordingly, one object of the present invention is to provide an improved water-resistant rocker switch for a timepiece.
Another object of the invention is to provide an improved switch for a watch which is not subject to actuation by water pressure.
Another object of the invention is to provide an improved rocker switch for a timepiece providing improved electrical contact and resistance to leakage.